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48 CHAPTER 2 Mind, Brain, Autonomous Agents, and Mental Disorders
FIGURE 2.8
Complementary computational properties of visual boundaries and surfaces. Visual
boundaries and surfaces are computed by the interblob and blob cortical processing
streams,respectively,thatoccurwithinand between corticalareas V1,V2,andV4.Anillusory
square is completed in response to the configuration of black and blue (gray in print version)
arcs that form the image. When this happens, breaks, called end gaps, occur in the
boundaries where the black arcs touch the blue (gray in print version) arcs. Blue (gray in
print version) color can then flow out of the blue (gray in print version) arcs to fill-in the
interior of the illusory square. The resulting percept of neon color spreading illustrates
complementary properties of boundary completion and surface filling-in Refs. [31,44],
namely: boundaries are completed in an oriented way, inward between pairs or greater
numbers of inducers with similar orientational preferences, and are insensitive to contrast
polarity, in the sense that they pool over opposite contrast polarities using V1 complex cells
at each position. In contrast, surfaces fill-in brightness and surface color in an unoriented
way, outward from individual contrastive inducers, and are sensitive to contrast polarity,
indeed support the visible qualia that observers can consciously see. These three pairs of
boundary and surface properties (oriented vs. unoriented, inward vs. outward, insensitive
vs. sensitive to contrast polarity) are manifestly complementary. Properties that are needed
to complete a boundary cannot be used to fill-in a surface, and vice versa. On the other
hand, boundaries and surfaces need to reciprocally interact across the interblob and blob
stream for either of them to generate a useful percept.
12. TOWARDS AUTONOMOUS ADAPTIVE INTELLIGENT
AGENTS AND CLINICAL THERAPIES IN SOCIETY
The above summary suggests that a firm foundation has been built over the past
50 years whereby discoveries about mind and brain can greatly influence the
